A voluntary association of



Dec. 27, 1927; Re. 16,830

M. A. LAABS PROCESS OF PRODUCING MONOCENTRIC FUSED BIFOCAL LENSES ori inai Filed Aug. 22. 1924 Zlvmwntom R 15. may (Lbaab UNITED STATES PATENT. OFFICE.

MAX A. LAABS, F SOUTHBRIDGE, MASSACHUSETTS, ASSIGNOR TO AMERICAN OPTICAL COMPANY, OF SOUTHBRIDGE, MASSACHUSETTS, A VOLUNTARY ASSOCIATION'OI';

' MASSACHUSETTS.

rnocnss or PRODUCING nonocnnrnrc Frisian nrrocan LENSES.

Original m5. 1,680,706, dated Ma a 1927, Serial 1%. 733,566, filed Au gust 22, 1924. Application for I reissue fi1ed'Novembcr'14 1927. Serial No. 233,289.

.The present invention relates to an improved monocentric or monaxiiil fused 'mul tifocal lens and blank, and has particular reference to the process of manufacture thereof. i

An important; object of the tion is to provide such a. monocentrio fused multifocal wherein the line dividing the reading and distance portions of the said lens passes through the optical center of the reading portion, and resides particularly in the process of manufacture of the lens '-,in such a manner that the optical center can be accurately produced. Another very important object of the invention is to provide an improved process for forming a monocentrie fused 'mnltifocal lens of this character that will greatly ex-' pedite the construction of such lenses, and that will forma neater and more lens for use as an ophthalmic lens.-

Other objects and advantages of the inventionwill become. apparent "during the course of-the following descri tion. In the drawings, wherein ike numerals are employed. to throughout the same: v Fig. 1 is a plan view showing the first step in the manufacture of such lensesf. Fig. 2 is a-view showing the second step. Fig. 3 shows a completedlens. Fig. 4 is a. section on line 4-4 in Fig. 3.. Prior to my invention attempts have been ,made to form such monoce itric fused bifocals, but .none of the inethodsused has been entirely satisfactory. In accordance with the present invention I take. .a

major blank 5 and grind a suitable recess or countersink in thegeometrical"center of the blank 5. After the countersink has been formed I fuse a button 6 therein, as is clearly shown in Fig. f Y been fused in the countersink, I divide the blank into halves, going through the geo- V metrical center of the blank andbutton- 1 preferably form the major blank 5 from crown'glass and fuse a button or segment 6 of flint glass therein, although the invention is not necessarily restricted to these two types of glass.

After the separation of the blank as above described, I take a semi-circular piece present invenpleasing" designate like parts.

After the button 6 has of crown glass 7 of the same refractivein dex as the part 5, and grind and polish the edge 8 until a smooth, even edge is presented. Likewise, after the separation of the blank, I grind and polish the edge 9 thereof so thatthe. edges 8 and 9 \vill'fit snugly together. The part 7 and the semiblank 5 are then fused at the edges 8 and 9 to present the lens 10 shown in Figs. 3 and 4. Due to the fact that theedges 8 and 9 are ground and polished, there will hiezno field of aberration between the segment 6 and the portion? fused to the blankb and segment 6 as shown in Fig. 4. Thelprocess employed' here will give a monoeentric lens having a line of' joinder between the segment 6 and portion 7, passing directly through the optical axis of the said segment. a 1' ,;It isto be understood that the relations of the glasses ab'ove'described do not necesglass, or in fact any. arrangement .of flint "and crown can be used aszlong as 7 and 5 areof the same index of refraction so they will fuse together -without visible lineof joinder, the invention residing in the fusing 'of the segment 6 on the geometrical center sarily have to be followed out, as all three' of the. sections can be "formed from'flint of the blank 5, separating the blank through i the geometrical center, and then fusing 'a .semi circulardisc tothe halves.

,It is to be understood that the form of the invention herewith shown and described is to be taken as the preferred embodiment of the same, and that various changes in the size,"shape and arrangement of parts may be resorted to Without departing from the spirit of the invention or the scope of the subjoind .clainis. 4

.Having thus described "my invention, I claim: x

a. segment of one index of refraction to a ti l major blank of different index, separating the major blank. and segment through the geometrical center of the segment, and then fusing a piece of glass of same index as the major blank to the separated edge.

LU L

2. The process of producing monaxial fused multifocal lenses consi'sting in fusing a flint glass segment in a crown glass major blank, separating the \blank and segmentthrough the geometrical center of the segment, and then fusing crown glass of same index of refraction as the first crownglass to the halves of the blank and segment.

3. The process of producing monaxial fused multifocal lenses, consisting in fusing a segment in a major blank, separating the major blank and segment through the geometrical center of thesegment, then grinding and polishing the-separated edge and fusing a piece of glass to the said edge.

4. The process of producing. monaxial fused multifocal lenses consisting in forming a recess in a major blank, fusing 21 segment therein, separating the segment and major. portion through the geometrical cen- V ter of the segment, grinding and polishing the separated edge thereof, then grinding and polishing the edge of another piece of signature. v

glass, and then fusing the two ground and index of refraction to a major blank of differ'ent index of refraction, separating the major 'blank and. segment through the segment and then fusing a third piece to-the separated edge.

In testimony whereof I have afiixedmy MAX A. LAABS. 

